A listing of acronyms used herein follows the detailed description section. In current cellular radio environments there may be various user equipments (UEs) that are operating/coexisting in a given cell that have different capabilities. For purposes of the examples herein these different capabilities may be concisely summarized as UEs operating under 3GPP Release 8/9 and those operating under 3GPP Release 10. Release 10 enables UEs to operate simultaneously on multiple cells in what is termed Carrier Aggregation (CA) mode. In carrier aggregation the bandwidth available for use by the wireless network consists of multiple component carriers; a given Release 10 UE may be operating on one component carrier designated as a primary cell (Pcell) and one or more further component carriers designated as secondary cells (Scells). Other Release 10 UEs may be operating in a non-CA mode and thus on only one carrier. For conciseness, herein these are referred to as non-CA UEs while those UEs for which there are two or more configured and activated component carriers are CA UEs. In this environment the Release 8/9 UEs operate on only one component carrier and are also referred to as non-CA UEs.
Data transmitted to any of these UEs is over one or multiple data radio bearer (DRBs). DRBs can have an associated guaranteed bit rate (GBR) but some DRBs may not; for conciseness the latter are referred to herein as non-GBR DRBs. DRBs assigned with a given CA UE may be served by any one or more of the CA UE's multiple active component carriers or cells. In this manner DRBs are associated with a given UE rather than with a given component carrier; a single DRB assigned to a given CA UE may carry data to or from that UE on all of that CA UE's active component carriers. In general a given UE can have more than one DRB active at a given time, for example one high priority DRB for voice communications and another low priority DRB for social networking data updates.
One cellular access technology by the 3GPP is E-UTRAN, also known as LTE. In LTE the radio access node (traditionally the base station) is known as an eNodeB or eNB, and handles scheduling of uplink and downlink (UL and DL) radio resources for the various active UEs under its control. Conventional practice in LTE for allocating available radio resources by the eNodeB scheduler can result in either starvation of non-CA UE data bearers or not being able to meet the high throughput bit rate guarantees for GBR data bearers of CA UEs.
For example, if a CA UE has a highest priority in one serving cell for its assigned GBR data bearer but not in the other serving cell, it could be allocated radio resources in all serving cells to meet the quality of service (QoS) demand of its high bit-rate GBR data bearer(s). This can lead to starvation for some of the GBR or non-GBR data bearers of other UEs even though the other UEs may have a higher priority in the other serving cell than the scheduled CA UE GBR data bearer.
One seeming solution would be to schedule and allocate radio resources for GBR/non-GBR data bearers of CA or non-CA UEs in these UEs' respective serving cells in strict order of their priorities. An eNodeB may have admitted a high bit-rate GBR data bearer of a CA UE with the expectation that it could use a ‘fatter’ bit-pipe by utilizing radio resources from multiple serving cells. But if the radio channel conditions are poorer than expected in one or more serving cells, such a high bit-rate CA UE GBR data bearer's bit-rate guarantees may not be met to such an extent that the user experience may be adversely impacted. Another consideration is that there may be multiple UEs in a given cell, some having a GBR data bearer and some having a non-GBR data bearer. A situation may arise in that the non-GBR data bearers are not allocated due to continual high data volume needs of the GBR data bearers. What is needed in the art is a mechanism to ensure the guaranteed bit rates and quality of service requirements are still met while dealing more fairly in allocating radio resources among GBR data bearers of CA UEs and the GBR and non-GBR data bearers of non-CA UEs.